Information display system

Abstract

Provided is an information display system for unidirectionally displaying an image to the inside or outside of a space via a transparent projection target member provided in the space, the information display system being provided with: an image projection device (48) which is disposed inside the space, modulates a light beam from a light source (201), generates image light, and projects the image light; a transparent sheet disposed on an inner surface of a display region provided on a part of the member to be projected; and a light direction conversion unit (54) that directs the image light from the image projection device (48) toward the transparent sheet in the display region, and the image projection device (48) includes an image light characteristic conversion unit that converts the image light from the light source (201) into image light having a narrow diffusion angle and comprising a specific polarization component.

Description

Technical Field

[0001] The present invention relates to an information display system capable of displaying images inside or outside a store (space) by reflecting or transmitting images on a transparent component used to divide a space, such as a display window glass; further, it relates to a vehicle information display system capable of using the information display system to project image light onto the front glass (front windshield), rear glass (rear glass, rear windshield), side glass (side glass, side glass) or combiner of a car, train, airplane, etc. (hereinafter collectively referred to as a "vehicle") to display images inside or outside the vehicle. Background Art

[0002] As such an information display system, it is generally known to use a transparent or reflective screen to display an image. For example, according to Patent Documents 1 and 2 listed below, a transparent or reflective screen including a light diffusion layer containing a binder and microparticles is known.

[0003] On the other hand, regarding the vehicle information imaging device and the information display system formed by using the same, for example, according to the following patent document 3, a so-called head-up display (HUD) device is known, which projects image light onto the front windshield of the vehicle and the stacking mirror to form a virtual image to display traffic information such as route information and congestion information, and vehicle information such as the remaining fuel amount and the cooling water temperature. In such an information display device, in order to be able to observe the image information in the form of a virtual image for the purpose of reducing the movement of the driver's viewpoint, a structure is usually adopted in which an optical system including a concave mirror (playing the role of a convex lens) is used to project the image displayed on the image display device to the driver's viewpoint.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 6133522

[0007] Patent Document 2: Japanese Patent No. 6199530

[0008] Patent Document 3: Japanese Patent Application Publication No. 2015-194707 Summary of the invention

[0009] Technical problem to be solved by the invention

[0010] However, in the above-mentioned prior art magnified projection information display system or device, no consideration is given to how to efficiently transmit the image light to the observer to improve the efficiency of light utilization. As a result, there is a first technical problem, namely, it is difficult to reduce the power consumption of the image projection device including the light source in the system or device.

[0011] In addition, in vehicle information display devices represented by head-up displays, AR (Augmented-Reality) information composed of virtual images is displayed in a manner that does not hinder the driver's observation of the outside of the vehicle, but when displaying information such as maps, high resolution and high recognizability are also required. Therefore, liquid crystal display elements (liquid crystal display panels) are mostly used because they are easy to obtain high-quality images and are relatively cheap. On the other hand, small liquid crystal display elements are used to achieve component miniaturization, so the resolution of the resulting projected image will be insufficient, which clarifies the second technical problem, that is, it is not suitable for displaying high-resolution images such as those displayed on smartphones.

[0012] In addition, in the vehicle information display device of the head-up display type of the prior art, when the inclination angle of the front windshield is large (close to vertical), since the configuration location of the imaging device is limited to between the steering wheel and the front windshield, the image light from the imaging device may be reflected by the front windshield in a direction that cannot reach the driver's eyes, resulting in the inability to form a display system, thereby clarifying the third technical problem, that is, there are constraints on the vehicle structure on which the information display device can be installed.

[0013] In addition, the purpose of the vehicle information display device of the head-up display type of the prior art is not to display image information outside the vehicle. Therefore, in the case of wanting to display image information outside the vehicle, it is necessary to install an image display device such as a monitor inside the vehicle to display the image information through the glass of the vehicle. However, in this case, these image display devices will hinder the driver's field of vision, which is not suitable from the perspective of safe driving.

[0014] In addition, Patent Documents 1 and 2, which are prior arts, disclose a reflective screen or a transparent screen used in an information display device and including a light diffusion layer containing an adhesive and microparticles. However, no consideration is given to how to efficiently transmit image light to an observer, i.e., to improve the efficiency of light utilization. Furthermore, no teaching is given on the application of the screen in a vehicle and on the specific method, form, and structure of the application.

[0015] The present invention provides an information display system and a vehicle information display system using the information display system, which replaces the existing information display system and device, can display high-resolution image information even on the glass surface of a display window, and can improve the light utilization efficiency by efficiently transmitting the image light to the observer, so that the power consumption of the system and device including the light source and the image projection device can be greatly reduced. It is also intended to provide a vehicle information display system, which reduces power consumption by improving the light utilization efficiency, and can use the windshield including the front window glass, rear window glass, and side window glass of the vehicle, regardless of its inclination angle, to achieve a display that can be observed by passengers (co-passengers) including the driver inside the vehicle but cannot be observed from the outside of the vehicle, or can be observed from the outside of the vehicle but cannot be observed by passengers (co-passengers) inside the vehicle, that is, it can perform so-called one-way display.

[0016] Technical means of solving problems

[0017] In order to achieve the above-mentioned purpose, the present invention first provides an information display system, which displays images unidirectionally inside or outside the space via a transparent projection component constituting the space, comprising: an image projection device, which is arranged inside the space and modulates a light beam from a light source to generate image light for projection; a transparent sheet, which is arranged on the inner side surface of a display area provided in a part of the projection component; and a light direction conversion unit, which directs the image light from the image projection device toward the transparent sheet in the display area, wherein the image projection device includes an image light characteristic conversion unit for converting the image light from the light source constituting the image projection device into image light with a narrow diffusion angle and composed of specific polarization components.

[0018] In order to achieve the above-mentioned purpose, the present invention also provides a vehicle information display system, which uses a part of the transparent projection component constituting the vehicle as a display area to display information to the interior or exterior of the vehicle, and includes: an image projection device, which is arranged inside the vehicle and is used to project image light of the information; a transparent sheet, which is arranged on the inner side surface of the display area provided in a part of the projection component; and a light direction conversion unit, which converts the direction of the image light from the image projection device to go to the transparent sheet, wherein the image projection device includes an image light characteristic conversion unit, which is used to convert the image light from the light source constituting the image projection device into image light with a narrow diffusion angle and composed of specific polarization components.

[0019] Effects of the Invention

[0020] By adopting the present invention, a novel and highly usable information display system can be provided, which can display high-resolution image information even on a glass surface such as a display window, and can improve the light utilization efficiency by efficiently transmitting image light to the observer, thereby significantly reducing power consumption. Furthermore, by using the information display system, a vehicle information display system that can significantly reduce power consumption can be provided. As for the vehicle information display system, the vehicle windshield including the front window glass, rear window glass, and side window glass can be used to realize a display that can be observed by passengers (co-passengers) including the driver inside the vehicle but cannot be observed from the outside of the vehicle, or can be observed from the outside of the vehicle but cannot be observed by passengers (co-passengers) inside the vehicle, that is, so-called one-way display can be performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a diagram showing an example of the overall configuration of an information display system according to an embodiment of the present invention.

[0022] Figure 2 This is a diagram showing an example of a specific structure of a light source device included in the image projection device of the information display system.

[0023] Figure 3 This is a cross-sectional configuration diagram for explaining the structure and function of a light source for performing polarization conversion in an image projection device.

[0024] Figure 4 This is a cross-sectional configuration diagram for explaining the structure and function of a light source for performing polarization conversion in an image projection device.

[0025] Figure 5 This is a diagram showing an example of the structure of a lenticular lens included in the image projection device of the information display system.

[0026] Figure 6 The figures shown include a graph showing the image light diffusion characteristics of the image display device.

[0027] Figure 7 The figures shown include a graph showing the image light diffusion characteristics of the image display device.

[0028] Figure 8 This is a cross-sectional view for explaining the principle of a light direction conversion panel included in an image projection device of an information display system.

[0029] Fig. 9 This is a cross-sectional view showing an example of a schematic structure of a protection cover included in the image projection device of the information display system.

[0030] Fig.10 This is a diagram showing a coordinate system for measuring visual characteristics of a liquid crystal panel.

[0031] Fig.11 This is a diagram showing the luminance angle characteristics (up and down directions) of a general liquid crystal panel.

[0032] Fig.12 This is a diagram showing the angular characteristics (vertical direction) of the contrast of a general liquid crystal panel.

[0033] Fig.13 This is a diagram showing the luminance angle characteristics (left-right direction) of a general liquid crystal panel.

[0034] Fig.14 This is a diagram showing the angular characteristics (left-right direction) of the contrast of a general liquid crystal panel.

[0035] Fig.15 This is a cross-sectional view showing a structural example of a light direction limiting panel provided in an image display device of an information display system.

[0036] Fig.16 This is a cross-sectional view showing the structure of a one-way transparent sheet (reflective type) (Example 1) included in the image projection device of the information display system.

[0037] Fig.17 This is a cross-sectional view showing the structure of a one-way transparent sheet (reflective type) (Example 2) included in the image projection device of the information display system.

[0038] Fig.18 This is a cross-sectional view showing the structure of a one-way transparent sheet (transmission type) (Example 1) included in the image projection device of the information display system.

[0039] Fig.19 This is a cross-sectional view showing the structure of a one-way transparent sheet (transmission type) (Example 2) included in the image projection device of the information display system.

[0040] Fig. 20 This is a diagram showing an example in which the information display system is applied to a passenger car.

[0041] Fig.21 This is a diagram showing an example in which the image display device of the information display system is installed in the ceiling portion of a passenger car as a vehicle.

[0042] Fig. 22 This diagram shows a portion of a glass portion of a car where an image can be displayed when an image display device of an information display system is installed in a ceiling portion of a passenger car as a vehicle.

[0043] Fig.23 This is a diagram showing an example in which the image display device of the information display system is installed in the ceiling portion of a passenger car as a vehicle.

[0044] Fig.24 This diagram shows a portion of a glass portion of a car where an image can be displayed when an image display device of an information display system is installed in a ceiling portion of a passenger car as a vehicle.

[0045] Fig.25 This is a diagram showing an example in which the information display system is applied to a bus as a vehicle.

[0046] Fig.26 This is a diagram showing an example in which the information display system is applied to a train as a vehicle.

[0047] Fig. 27 The figures shown include a graph showing the wavelength distribution of natural light such as sunlight.

[0048] Fig.28 The figures shown include graphs showing the reflectivity of glass with respect to P-polarized light and S-polarized light of natural light such as sunlight.

[0049] Fig.29 This is a diagram showing an example of a specific configuration of a vehicle display system obtained by applying the information display system to a vehicle.

[0050] Fig.30 This is a diagram showing an example of a more specific structure of a vehicle display system obtained by applying the information display system to a vehicle.

[0051] Fig.31 This is a diagram showing an example in which the information display system is applied to a passenger car.

[0052] Fig.32 This is a diagram showing an example of the configuration of a vehicle display system that displays information to a driver through the windshield of the vehicle.

[0053] Fig.33 This is a diagram showing an example of the configuration of a vehicle display system that displays information to a driver and a monitor in a passenger seat through a front windshield of the vehicle.

[0054] Fig.34 This is a diagram showing an example of displaying information to the outside of a vehicle through the rear window glass of the vehicle.

[0055] Fig.35 This is a diagram showing the relationship between the size of a virtual image obtained by the information display system and the position at which the virtual image is generated.

[0056] Fig.36 This is a diagram showing an example in which a light direction limiting panel provided in an image display device of an information display system is provided in a vehicle together with the image display device. DETAILED DESCRIPTION

[0057] The following is a detailed description of the embodiments of the present invention using the accompanying drawings and the like. The present invention is not limited to the following description, and those skilled in the art can make various changes and modifications within the scope of the technical ideas disclosed in this specification. In addition, in all the drawings used to illustrate the present invention, the same reference numerals are marked on parts having the same functions, and their repeated descriptions are sometimes omitted.

[0058] <Information Display System>

[0059] Figure 1 The overall structure of an information display system of an embodiment of the present invention is shown. For example, in a store, the space is divided by a display window (also called "window glass") 220 composed of a light-transmitting component such as glass. The information display system of this embodiment can reflect or transmit through the transparent component to display an image unidirectionally inside or outside the store (space). In addition, the Figure 1 The state shown is that the inside of the display window 220 (inside the store) is the depth direction (far away), and the outside of the display window 220 (for example, the sidewalk) is the near side (in front of the eyes).

[0060] More specifically, if Figure 1 As shown, above the display window 220 made of transparent components such as glass, an image display device 48 including a light source and used to generate and project image light to be displayed, which will be described in detail later, is arranged. The image light generated by the image display device 48 is selectively displayed one-way to the inside or outside under the action of a light direction conversion panel 54 described in detail later or a transparent sheet (film) 51 attached to the display window 220. In this way, the display window 220 can be used to display various information inside or outside, which can significantly improve the utilization efficiency of the display window.

[0061] then, Figure 2 2 shows a more specific structure of the information display system, wherein the image display element 52 constituting a part of the image display device 48 is composed of, for example, a relatively large liquid crystal display panel having a screen size exceeding 6 inches. In addition, in order to be able to correct the distortion to a level that does not cause problems in actual use, the resolution of the panel is preferably 1280×720 or more.

[0062] In addition, the image display device 48 includes a light source device 101 constituting a light source thereof together with the liquid crystal display panel 52. Figure 2 In FIG. 1 , the light source device 101 is shown together with the liquid crystal display panel 52 as a developed stereoscopic view.

[0063] As will be described in detail later, the liquid crystal display panel (element) 52 is Figure 2As shown by the middle arrow 30, light from the backlight device, i.e., the light source device 101, is used to obtain an illumination light beam with strong directivity (straight-line travel) and a polarization plane unified in one direction, which has similar characteristics to laser light. The image light modulated according to the input image signal is emitted toward a transparent sheet 51 arranged on the surface of the window glass 220.

[0064] In addition, in the information display system, the Figure 2 4 shows a light direction conversion panel 54 to be described later together with a liquid crystal display panel 52 constituting the image display device 48, and may further include a narrow angle diffusion plate (not shown) as required, wherein the light direction conversion panel 54 is used to control the directional characteristics of the outgoing light beam from the light source device 101. That is, polarizing plates are provided on both sides of the liquid crystal display panel 52 so that the intensity of the light is modulated according to the image signal and the image light of a specific polarization is emitted (see Figure 2 30).

[0065] Thus, using light of a specific polarization with high directivity (linear propagation), a desired image is projected onto the window glass 220 via the light direction conversion panel 54, and is reflected or transmitted toward the eyes (not shown) of a monitor inside or outside the store (space) by means of the transparent sheet 51 provided on the surface thereof. In addition, a protective cover (not shown) is sometimes provided on the surface of the light direction conversion panel 54.

[0066] In this embodiment, in order to improve the utilization efficiency of the outgoing light beam 30 from the light source device 101 and significantly reduce power consumption, in the image display device 48 including the light source device 101 and the liquid crystal display panel 52, as described below, the light from the light source device 101 (see Figure 2 As shown in the arrow 30, the brightness of the image light to be transmitted or diffused in the transparent sheet 51 provided on the surface of the window glass 220 is provided with high directivity by using optical components such as a cylindrical lens described below. As a result, the image light from the image display device 48 reaches the observer inside the window 220 (inside the store) or outside the window 220 (for example, on the sidewalk) with high directivity (straight travel) like a laser, and as a result, a high-quality image can be displayed with high resolution, and the power consumption of the image display device 48 including the light source, that is, the LED element 201, is significantly reduced.

[0067] <Embodiment of Image Display Device>

[0068] Figure 3 1 shows the specific structure of the light source device 101. Figure 3 In the inclusion Figure 2The image display device 48 of the light source device 101 is provided with a liquid crystal display panel 52 and a light direction conversion panel 54. The light source device 101 is formed of, for example, plastic. Figure 2 The housing is shaped like a shell, and contains the LED element 201 and the light guide 203 described in detail later. Figure 2 As shown, a lens shape is provided to convert the divergent light from each LED element 201 into a substantially parallel beam, and the lens shape has a shape in which the cross-sectional area gradually increases as it goes in the direction opposite to the light receiving part, and has the function of gradually reducing the divergence angle by making the light propagate through multiple total reflections inside. A liquid crystal display panel 52 constituting the image projection device 48 is mounted on its upper surface.

[0069] In addition, on one side of the housing of the light source device 101 (at Figure 3 In the example, it is the left end face, an LED (Light Emitting Diode) element 201 as a semiconductor light source and an LED substrate 202 on which a control circuit of the LED element is mounted are provided, and in some cases a heat sink is also mounted on the outer side of the LED substrate 202, which is a component for cooling heat generated by the above-mentioned LED element and the control circuit.

[0070] On the other hand, a liquid crystal display panel frame (not shown) mounted on the upper surface of the housing of the light source device 101 is provided with a liquid crystal display panel 52 mounted on the frame and an FPC (Flexible Printed Circuits: Flexible Printed Circuit Board) (not shown) electrically connected to the liquid crystal display panel. That is, as described in detail later, the liquid crystal display element, i.e., the liquid crystal display panel 52, together with the solid light source, i.e., the LED element 201, modulates the intensity of the transmitted light to generate a display image based on a control signal sent from a control circuit (not shown here) configured as an electronic device. At this time, since the generated image light has a narrow diffusion angle and only has a specific polarization component, a new image display device that is close to a surface-emitting laser image source driven by an image signal and that is not available in the prior art can be obtained.

[0071] In addition, under the current circumstances, it is impossible to obtain a laser beam of the same size as the image obtained by the above-mentioned image display device 48 from the perspective of safety. Therefore, in this embodiment, a light beam emitted by a common light source including an LED element is used to obtain light close to the above-mentioned surface-emitting laser image light.

[0072] <Lenticular lens>

[0073] In order to control the diffusion distribution of the image light from the liquid crystal display panel 52, a light source 101 is provided between the light source device 101 and the liquid crystal display panel 52 or on the surface of the liquid crystal display panel 52. Figure 5 By optimizing the lens shape of the cylindrical lens 800 shown in the figure, the emission characteristics of the image light in one direction (the image light in the X-axis direction in the figure) can be controlled. Furthermore, by configuring the microlens array in a matrix, the emission characteristics of the image light beam from the image projection device 48 in the x-axis and y-axis directions can be controlled, and as a result, an image display device with a desired diffusion characteristic can be obtained.

[0074] Next, refer to the above Figure 3 and Figure 4 , the structure of the optical system housed in the casing of the light source device 101 is described in detail.

[0075] Figure 3 and Figure 4 Since this is a cross-sectional view, only one of the multiple LED elements 201 constituting the light source is shown, and as described above, the light emitted by them can be converted into substantially collimated light by the shape of the light receiving end surface 203a of the light guide 203. Therefore, the light receiving portion of the end surface of the light guide and the LED element are installed to maintain a predetermined positional relationship.

[0076] The light guides 203 are each formed of a translucent resin such as acrylic. Moreover, the LED light receiving surface at the end of the light guide has, for example, an outer peripheral surface of a convex cone shape obtained by rotating a parabolic cross section, a concave portion at the top, and a convex portion (i.e., a convex lens surface) formed in the central portion of the concave portion, and a convex lens surface protruding outward (or a concave lens surface recessed inwardly) (not shown) in the central portion of its planar portion. In addition, the outer shape of the light receiving portion of the light guide on which the LED element 201 is mounted is a parabolic shape that can form a conical outer peripheral surface, and the parabola is set within an angle range that can make the light emitted from the LED element to the surrounding direction fully reflected inside it, or a reflecting surface is formed.

[0077] On the other hand, the LED elements 201 are arranged at predetermined positions on the surface of the circuit board, i.e., the so-called LED substrate 202. The LED substrate 202 is arranged and fixed to the LED collimator (light receiving end surface 203a) so that the LED elements 201 on the surface are located in the center of the above-mentioned recess.

[0078] According to this configuration, by utilizing the shape of the light receiving end surface 203 a of the light guide 203 , the light emitted from the LED element 201 can be output as substantially parallel light, and the utilization efficiency of the generated light can be improved.

[0079] As described above, the light source device 101 is provided with a light source unit formed by arranging a plurality of LED elements 201 as light sources at the light receiving end surface 203a as a light receiving unit provided at the end surface of the light guide 203, and the divergent light beam from the LED element 201 is made into approximately parallel light by utilizing the lens shape of the light receiving end surface 203a of the light guide end surface, and the light beam is guided inside the light guide 203 (in a direction parallel to the paper surface) as indicated by the arrow, and is emitted toward the liquid crystal display panel 52 (in a direction perpendicular to the paper surface) arranged approximately parallel to the light guide by utilizing the light beam direction converting unit 204. Furthermore, by optimizing the distribution (density) of the light beam direction converting unit 204 by utilizing the shape inside or on the surface of the light guide, the uniformity of the light beam incident on the liquid crystal display panel 52 can be controlled.

[0080] Figure 3 2 is a cross-sectional configuration diagram for explaining the structure and function of the light source of this embodiment that performs polarization conversion in the light source device 101 including the light guide 203 and the LED element 201. Figure 3 In the figure, the light source device 101 includes, for example, a light guide 203 formed of plastic or the like and having a light beam direction conversion portion 204 arranged on the surface or inside, an LED element 201 as a light source, a reflective sheet 205, a phase difference plate 206, the above-mentioned cylindrical lens 800, etc., and a liquid crystal display panel 52 with polarizing plates arranged on the light source light incident surface and the image light emitting surface is installed on its upper surface, thereby constituting an image projection device 48.

[0081] A reflective polarizing plate 49 in the form of a thin film or sheet is provided on the light source incident surface (the lower surface in the figure) of the liquid crystal display panel 52 corresponding to the light source device 101, which selectively reflects polarized light (for example, P light) 212 in one direction in the natural light beam 210 emitted from the LED light source 201, and further reflects it from a reflective sheet 205 provided on a surface (the lower surface in the figure) of the light guide 203, and goes to the liquid crystal display panel 52 again.

[0082] Therefore, a phase difference plate (λ / 4 plate) 206 is provided between the reflector 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49, so that the reflected light beam is reflected by the reflector 205 and passes through the phase difference plate 206 twice, and can be converted from P polarized light to S polarized light, thereby improving the utilization efficiency of the light source light as the image light. Figure 1 As shown, the image light beam ( Figure 3 The light is incident on the window glass 220 at a larger incident angle, so the reflectivity on the transparent sheet 51 is larger, and good diffusion characteristics can be obtained for monitoring inside or outside the store (space).

[0083] Figure 4 and Figure 3 Likewise, it is a cross-sectional configuration diagram for explaining the structure and operation of the light source of this embodiment that performs polarization conversion in the light source device 101 including the light guide 203 and the LED element 201 . Figure 4 The light source device 101 is similarly composed of, for example, a light guide 203 formed of plastic or the like and having a light beam direction conversion portion 204 disposed on the surface or inside thereof, an LED element 201 as a light source, a reflective sheet 205, a phase difference plate 206, the above-mentioned cylindrical lens 800, etc., on the upper surface of which is mounted a liquid crystal display panel 52 having polarizing plates disposed on the light source light incident surface and the image light emitting surface, thereby constituting an image projection device 48.

[0084] A thin film or sheet-like reflective polarizing plate 49 is provided on the light source incident surface (lower surface in the figure) of the liquid crystal display panel 52 corresponding to the light source device 101, which selectively reflects polarized light (e.g., S light) 211 in one direction in the natural light beam 210 emitted from the LED light source 201, and further reflects it from a reflective plate 205 provided on one surface (lower surface in the figure) of the light guide 203, and sends it to the liquid crystal display panel 52 again. A phase difference plate (λ / 4 plate) is provided between the reflective plate 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49, so that the reflected light beam is reflected by the reflective plate 205 and passes through the phase difference plate twice, and can be converted from S polarized light to P polarized light, thereby improving the utilization efficiency of the light source light as the image light. Even if the image light beam (arrow 214 in the figure) to which the light intensity is modulated by the liquid crystal display panel 52 based on the image signal is Figure 1 As shown, the image light is incident on the window glass 220 at a larger incident angle, which can also reduce the reflection on the surface and can use the transparent sheet 51 to efficiently diffuse the image light to the outside.

[0085] Here, Figure 5 The function of the cylindrical lens 800 shown in FIG. 8 is described below. The cylindrical lens 800 can efficiently reflect or diffuse the light emitted from the image display device 48 on the transparent sheet 51 on the window glass 220 by optimizing the lens shape. That is, for the image light from the image projection device 48, as shown in FIG. Figure 6 As shown in (a) and (b), for example, by combining two cylindrical lenses or arranging a microlens array in a matrix to set up a sheet with controllable diffusion characteristics, the brightness (relative brightness) of the image light can be controlled according to the reflection angle in the X-axis and Y-axis directions (the vertical direction is 0 degrees).

[0086] In this embodiment, by using such a cylindrical lens 800, compared with the prior art, Figure 6As shown in (b), the brightness characteristics in the vertical direction are made steeper, and the balance of the directional characteristics in the up and down directions (positive and negative directions of the y-axis) is changed (becomes unbalanced) to reduce reflection and diffusion to increase the brightness of the light (relative brightness). This allows the formation of image light with a narrow diffusion angle (high linear propagation) and only a specific polarization component, like the image light from a surface-emitting laser image source, which can efficiently reach the eyes of the observer.

[0087] In addition, using the above light source device, Figure 6 The outgoing light diffusion characteristics of a conventional liquid crystal panel shown in (a) and (b) (in Figure 6 Compared with the prior art (marked as the prior art), by forming a directional characteristic with greatly narrowed angles in both the x-axis direction and the y-axis direction as shown in Examples 1 and 2, it is possible to realize an image display device that can emit an image light beam that is nearly parallel to a specific direction, and the image light beam is light of a specific polarization.

[0088] Figure 7 An example of the characteristics of the cylindrical lens used in this embodiment is shown. In this example, the characteristics in the X direction (vertical direction) are particularly shown, and the characteristic O represents the brightness characteristic in which the peak of the light emission direction is located at an angle of about 30 degrees upward from the vertical direction (0 degrees) and is symmetrical up and down. In addition, Figure 7 Characteristics A and B of FIG. 1 and FIG. 2 further focus the image light above the peak brightness near 30 degrees to increase the brightness (relative brightness). Therefore, in these characteristics A and B, at an angle exceeding 30 degrees, the brightness (relative brightness) of the light decreases sharply compared to characteristic O.

[0089] That is, by using an optical system including the above-mentioned cylindrical lens, the image light from the image projection device 48 can be reflected or diffused in a manner that the brightness is increased (emphasized) in a specific direction through the transparent sheet 51 on the window glass 220 described later. As a result, the image light from the image projection device 48 can be efficiently reached by the eyes of the observer outdoors or indoors as light with a narrow diffusion angle (high linear propagation) and only a specific polarization component, just like the image light from the surface-emitting laser image source. As a result, even if the intensity (brightness) of the image light from the image projection device 48 is reduced, the observer can accurately identify the image light to obtain information. In other words, by further reducing the output of the image projection device 48, an information display system with lower power consumption can be achieved.

[0090] <Light direction conversion panel>

[0091] Figure 8This is a schematic diagram for explaining the principle of the light direction conversion panel 54, which constitutes a part of the information display system of this embodiment and is arranged on the upper surface of the above-mentioned image display device 48. The light beam from the light guide 203 of the above-mentioned light source device 101 is incident from the incident surface (lower surface in the figure) of the light direction conversion panel 54, and the light beam is refracted in the desired direction θ3 under the lens action of the linear Fresnel lens arranged on the exit surface (upper surface in the figure). At this time, based on Snell's law, the desired direction θ3 can be uniquely derived according to the incident angle θ2 of the light beam on the Fresnel lens, the Fresnel angle θ0 of the Fresnel lens, and the refractive index n of the substrate.

[0092] As a result, it is possible to provide the substantially parallel light beam from the light guide with directivity to a desired direction. That is, the image light from the liquid crystal display panel 52 constituting the image display device 48, which is composed of light having a high straight-line property and only having a specific polarization component, can be directed to the transparent sheet 51 provided on the window glass 220 described below without being observed by the observer inside or outside the store (space). Thereafter, the image light is reflected and diffused in one direction by the transparent sheet 51, and its reflected image is observed by the observer.

[0093] That is, the light direction conversion panel 54 is used to convert the light from the image display device 48 (see Figure 1 ) can be observed directly from the space, so that the observer in the store can monitor only the reflected image generated by the reflected light. In addition, by providing a light-absorbing paint or pigment on the connecting surface 88 of the Fresnel lens, the generation of light other than the light beam traveling in the desired direction is suppressed. As a result, unnecessary light is not mixed in the image light reflected by the window glass 220, so the imaging performance is not impaired.

[0094] <Protective cover>

[0095] Fig. 9 : is a cross-sectional view showing a schematic structure of the protective cover 50 provided on the upper surface of the above-mentioned light direction conversion panel 54. A black stripe 59 is provided on a portion of the light emitting side of the substantially transparent substrate 56. In order to reduce the surface reflection of external light including sunlight, the black stripe 59 can use a paint containing carbon black as a black paint. In addition, in the portion where the black stripe is not provided, an anti-reflection film is provided to suppress surface reflection, thereby greatly reducing the reflection of external light on the surface of the protective cover 50, and the problems caused by the reflection of external light are reduced. On the other hand, in order to enhance the light shielding performance against sunlight, the anti-reflection film can have the characteristics of reflecting near-infrared light and infrared light.

[0096] On the other hand, a film or thin film 50a for absorbing or reflecting the P light component in the sunlight beam is formed or attached to the light incident side (lower side in the figure) of the substantially transparent substrate 56. As a result, the P light component of the sunlight and the like are not incident on the image projection device 48, so the reliability in terms of light resistance and heat resistance is greatly improved. On the other hand, since a filter characteristic for selectively transmitting the S-polarized image light output from the image projection device 48 is also provided, the contrast performance of the obtained image is greatly improved.

[0097] However, in a conventional TFT (Thin Film Transistor) liquid crystal panel, the brightness and contrast performance vary depending on the direction of light emission due to the characteristics of the liquid crystal and the polarizing plate. Fig.10 In the evaluation under the measurement environment shown in the figure, the characteristics of the panel's vertical brightness and viewing angle are as follows: Fig.11 As shown, the characteristics are most excellent at an angle slightly offset from the vertical angle of the panel surface (0 degree angle of emission). This is because the characteristics of light twisting in the vertical direction of the liquid crystal will not reach 0 degrees when the applied voltage is maximum.

[0098] On the other hand, the contrast performance in the up and down directions is as Fig.12 As shown, the performance is excellent in the range of -15 to +15 degrees. If the brightness characteristics are also considered, the best performance can be obtained when the performance is used in the range of ±10 degrees with 5 degrees as the center.

[0099] In addition, the characteristics of the panel's brightness and viewing angle in the left and right directions are as follows Fig.13 As shown, the characteristics are most excellent at an emission angle perpendicular to the panel surface (emission angle 0 degrees). This is because the characteristic of twisting light in the left-right direction of the liquid crystal is 0 degrees when the applied voltage is the maximum.

[0100] Similarly, the contrast performance in the left and right directions is Fig.14 As shown, it is excellent in the range of -5 degrees to -10 degrees. If the brightness characteristics are also considered, the best characteristics can be obtained when used in the range of ±5 degrees with -5 degrees as the center. Therefore, for the emission angle of the image light emitted from the liquid crystal panel, the light beam direction converter 204 provided in the light guide 203 of the light source device 101 is used to make the light incident on the liquid crystal panel from the direction in which the best characteristics can be obtained, and the light is modulated based on the image signal, so that the image quality and performance of the image display device 48 can be improved.

[0101] In order to bend the image light emitted from the liquid crystal panel as the image display element to a desired direction, a light direction conversion panel 54 may be provided on the emission surface of the liquid crystal panel.

[0102] <Image light control film>

[0103] Fig.15 2 is a cross-sectional view of an image light control film 70 that has the function of limiting the emission direction of image light. The image light control film 70 is provided, for example, on the upper surface of the image display device 48, so that the image light from the liquid crystal display panel 52 is emitted in a specific direction (in the direction of the hollow arrow in the figure), and a part of the light is blocked by the black portion 70b, so that it does not directly enter the eyes of the observer, thereby preventing the light from the image display device 48 from directly entering the eyes of the observer and causing problems.

[0104] The image light control film 70 has the function of preventing the image light from going directly to the observer. On the other hand, the image light passes through the transparent portion 70a and is reflected by the front window glass 6, etc., so that the driver who is the observer can recognize the image light. As the image light control film 70, for example, a view angle control film (VCF: View Control Film) of Shin-Etsu Polymer Co., Ltd. is suitable. Its structure is to alternately configure transparent silicon and black silicon, and configure synthetic resin on the light incident and emission surfaces to form a sandwich structure, so it is expected to achieve the same effect as the image light control film 70 of this embodiment.

[0105] The spacing h between the transparent portion 70a and the black portion 70b of the viewing angle control film is preferably less than 1 / 3 of the pixels of the image to be displayed. At this time, regarding the thickness W, when it is desired to obtain a viewing angle α greater than 90 degrees, h / w is greater than 1.0, and when it is desired to obtain a viewing angle α less than 90 degrees, h / w is less than 1.0. On the other hand, the haze (HAZE) of the transparent sheet 51, which is defined by the ratio of the diffuse transmittance to the parallel light transmittance, is practically no problem as long as it is less than 10%, but it is preferably less than 4%.

[0106] <One-way transparent sheet: Example 1 of reflective type>

[0107] Next, in the overall structure of the information display system of this embodiment, the structure and function of the transparent sheet 51 are particularly described. Fig.16 Here, the S-polarized light of the sunlight incident on the window glass 220 from an oblique direction is reflected, and the P-polarized light is transmitted to the transparent sheet 51. The transparent sheet 51 is composed of a polarizing plate 57 that transmits the S light, a transparent diffusion sheet 55, and a phase difference plate 58.

[0108] The transparent sheet 51 uses a film formed by melting and stretching a thermoplastic polymer dispersed with zirconium oxide nanoparticles or diamond nanoparticles having a large refractive index, such as "KALEIDOSCREEN" manufactured by JXTG Energy Co., Ltd. (refer to the above-mentioned patent document 3). It is transparent when no image is displayed, and does not hinder the observer from monitoring the scenery outside the store (outside the store). On the other hand, when the image is displayed, the image light is diffused and reflected to allow the observer inside or outside the store (space) to identify the image information, that is, the so-called one-way display can be achieved. At this time, the haze (HAZE) of the transparent sheet 51, which is defined by the ratio of the diffuse transmittance to the parallel light transmittance, is not a problem in practical use as long as it is less than 10%, but it is preferably less than 4%.

[0109] The image light from the image projection device 48 is S-polarized light, so when it is incident at an angle, it is scattered in the transparent diffusion sheet 55 with a high reflectivity and emitted toward the observer. On the other hand, a part of the image light has its polarization direction disturbed by scattering, and is diffused and transmitted through the transparent diffusion sheet 55 and emitted toward the window glass 220. Since the refractive index difference is small at the incident surface of the window glass 220, the degree of double images caused by the reflected light is low.

[0110] In contrast, the intensity of the reflected light generated on the exit surface (surface in contact with the outside world) of the window glass 220 is mostly S-polarized components, so the reflectivity is high. The image light reflected on this surface is absorbed when it passes through the polarizing plate 57 again after reflection, so it will not return to the observer side. Therefore, the light intensity of the double image generated by the reflected image of the window glass 220 can be greatly reduced, so the image quality is greatly improved. In addition, similarly, as a reflection surface of the image, the above-mentioned transparent sheet 51 is pasted on the stacking mirror instead of the window glass 220, and of course the same effect can be obtained.

[0111] By using the transparent sheet 51 described above, under specified conditions during the day, the P-polarized sunlight component of the light passing through the window glass 220 (in the stacking mirror mode, it also passes through the stacking mirror after passing through the window glass) is absorbed before the information display system and the light direction conversion panel 54 and the protective cover 50 arranged on its upper surface, thereby preventing it from returning to the liquid crystal display panel and the polarizing plate.

[0112] <One-way transparent sheet: Example 2 of reflective type>

[0113] use Fig.17 Example 2 of the reflective type of the one-way transparent sheet is described. In this example, a further Fig.15 The image light control film 70 shown is used to form an external light control film (hereinafter, indicated by reference numeral 70 ).

[0114] As described above, the sunlight incident on the window glass 220 from an oblique direction has its S polarized light reflected and its P polarized light transmitted to the transparent sheet 51. At this time, the black area 70b (in the middle) provided in the external light control film 70 Fig.17 The light (displayed in gray) is absorbed and does not reach a room or vehicle equipped with an image display device.

[0115] In addition, since it will not mix with the image light from the image display device 48, it is also possible to prevent the image quality from being reduced. The transparent sheet 51 is composed of a transparent diffusion sheet 55. The transparent sheet 51 uses a film made by melting and stretching a thermoplastic polymer in which zirconium oxide nanoparticles or diamond nanoparticles with a large refractive index are dispersed, such as the "KALEIDO SCREEN" manufactured by JXTG Energy Co., Ltd. (refer to the above-mentioned patent document 3). When the image is not displayed, it is transparent and does not hinder the observer from monitoring the scenery outside (outside the store). On the other hand, when the image is displayed, the image light is diffused and reflected to allow the observer inside or outside the store (space) to recognize the image information, that is, the so-called one-way display can be achieved.

[0116] When the observer monitors the outside scenery, the outside light passes through the transparent part 70a, so the outside scenery monitoring will not be hindered. As the outside light control film 70, for example, the view angle control film (VCF: View Control Film) of Shin-Etsu Polymer Co., Ltd. is suitable. Its structure is to alternately arrange transparent silicon and black silicon, and arrange synthetic resin on the light incident and emission surfaces to form a sandwich structure, so it is expected to achieve the same effect as the external light control film 70 of this embodiment. The spacing h between the transparent part 70a and the black part 70b of the above-mentioned view angle control film is preferably less than 1 / 3 of the pixels of the image to be displayed. At this time, with respect to the thickness W, when it is desired to obtain a view angle α greater than 90 degrees, h / w is greater than 1.0, and when it is desired to obtain a view angle α less than 90 degrees, h / w is less than 1.0.

[0117] On the other hand, the haze (HAZE) defined by the ratio of the diffuse transmittance to the parallel light transmittance of the transparent sheet 51 is 10% or less, which is not a problem in practice, but is preferably 4% or less. In addition, when the transparent sheet 51 is pasted on the front window glass for vehicle use, the total transmittance needs to be 75% or more.

[0118] The image light from the image projection device 48 is S-polarized light, so when it is incident at an angle, it is scattered in the transparent diffusion sheet 55 with a high reflectivity and emitted toward the observer. On the other hand, a part of the image light has its polarization direction disturbed by scattering, and is diffused and transmitted through the transparent diffusion sheet 55 and emitted toward the window glass 220. Since the refractive index difference is small at the incident surface of the window glass 220, the degree of double images caused by the reflected light is low.

[0119] In contrast, the intensity of the reflected light generated on the exit surface (surface in contact with the outside world) of the window glass 220 is mostly S-polarized components, so the reflectivity is large. The image light reflected on this surface is absorbed by the black area 70b when passing through the polarizing plate 57 again after reflection, so it will not return to the observer side. Therefore, the light intensity of the double image generated by the reflected image of the window glass 220 can be greatly reduced, so the image quality is greatly improved. In addition, similarly, as a reflection surface of the image, the above-mentioned transparent sheet 51 is pasted on the stacking mirror instead of the window glass 220, and of course the same effect can be obtained.

[0120] By using the transparent sheet 51 described above, under specified conditions during the day, the P-polarized sunlight component of the light passing through the window glass 220 (in the stacking mirror mode, it also passes through the stacking mirror after passing through the window glass) is absorbed before the information display system and the light direction conversion panel 54 and the protective cover 50 arranged on its upper surface, thereby preventing it from returning to the liquid crystal display panel and the polarizing plate.

[0121] <One-way transparent sheet: Transmission type example 1>

[0122] Fig.18 The structure of the transparent sheet 51' that diffuses the image light beam to the outside of the vehicle or outdoors is shown. A polarizing plate 57 and a phase difference plate 58 that transmit P light are provided on the image light beam incident surface of the transparent diffusion sheet 55 to prevent the image light beam reflected on the transparent diffusion sheet 55 from returning to the room (the space where the information display device is provided). As a result, the image presented on the window glass 220 will not cause an obstacle to the observer. Regarding the optimal phase difference of the phase difference plate 58 provided between the polarizing plate 57 and the transparent diffusion sheet 55, the optimal value can be selected according to the diffusion characteristics of the transparent diffusion sheet. When the diffusion angle is large, it is preferably close to λ / 4. When the diffusion angle is small, good conversion performance can be obtained by combining with a λ / 8 plate or the like.

[0123] In addition, instead of the above-mentioned transparent diffusion sheet 55, a sheet to which a reflection-enhancing coating for improving the reflectivity of a specific polarization is applied is used as a substitute for the above-mentioned polarizing plate, or the reflection-enhancing coating is provided on the surface of the polarizing plate. This can increase the reflectivity of the image light beam and, at the same time, can greatly reduce the intensity of the double image produced by the reflected image of the window glass 220. That is, it can be confirmed that the same effect as the above-mentioned technology can be obtained.

[0124] Furthermore, instead of the transparent diffusion sheet 55, for example, PDLC (Polymer Dispersed Liquid Crystal) of Santech Display Co., Ltd. can be used, and no voltage is applied in the image display state to disperse the image light, and a voltage is applied in the image non-display state to form a transparent state to replace the transparent sheet. In addition, the author found through experiments that by making the voltage applied to the PDLC variable to make the dispersion characteristics variable, and modulating the applied voltage synchronously with the ON / OFF or strength of the image signal, a screen with a new function that can change the transmittance according to the image can be realized.

[0125] <One-way transparent sheet: Transmission type example 2>

[0126] Fig.19 A transparent sheet 51' is shown for diffusing the image beam to the outside of the vehicle or outdoors, wherein the Fig.15 The image light control film 70 shown in the figure is used as an external light control film (hereinafter referred to as 70). As described above, the sunlight incident on the window glass 220 from an oblique direction is reflected by its S polarized light and transmitted by its P polarized light to the transparent sheet 51. At this time, the black portion 70b (in the middle of the black portion 70b) provided in the external light control film 70 is Fig.19 The light is absorbed by the image display device (shown in gray in the figure) and does not reach the room or the car where the image display device is installed. In addition, since it does not mix with the image light from the image display device 48, it is also possible to prevent the image quality from being reduced. The transparent sheet 51' is composed of a transparent diffusion sheet 55.

[0127] The transparent sheet 51' uses a film made by melting and stretching a thermoplastic polymer in which zirconium oxide nanoparticles or diamond nanoparticles with a high refractive index are dispersed, such as "KALEIDOSCREEN" manufactured by JXTG Energy Corporation (refer to the above-mentioned patent document 3). It is transparent when no image is displayed and does not hinder the observer from monitoring the scenery outside (outside the store). On the other hand, when the image is displayed, the image information is diffused and reflected to enable observers inside or outside the store (space) to identify the image information, that is, it can achieve so-called one-way display.

[0128] In the above-mentioned external light control film 70, the image light incident on the window glass 220 from an oblique direction passes through the transparent part 70a without being shielded by the black part 70b, so it can be diffused by the transparent sheet 51', and the image display facing the outside world (outside the car or outside the store) can be performed. As the external light control film 70, for example, the view angle control film (VCF: View Control Film) of Shin-Etsu Polymer Co., Ltd. is suitable. Its structure is to alternately arrange transparent silicon and black silicon, and arrange synthetic resin on the light incident and emitting surfaces to form a sandwich structure, so it is expected to achieve the same effect as the external light control film of this embodiment.

[0129] The spacing h between the transparent portion 70a and the black portion 70b of the viewing angle control film described above is preferably less than 1 / 3 of the pixel of the image to be displayed. At this time, regarding the thickness W, if it is desired to obtain a viewing angle α greater than 90 degrees, h / w is made greater than 1.0, and if it is desired to obtain a viewing angle α less than 90 degrees, h / w is made less than 1.0. In addition, by making the inclination angle γ of the black portion consistent with the incident angle of the image light determined by the installation position of the image display device 48 and the window glass, energy loss can be reduced.

[0130] On the other hand, the haze (HAZE) of the transparent sheet 51, which is defined by the ratio of the diffuse transmittance to the parallel light transmittance, is not a problem in practical use as long as it is 10% or less, but it is preferably 4% or less. In addition, by replacing the above-mentioned transparent diffuser sheet 55 with a sheet having a reflection enhancement coating applied thereto for increasing the reflectivity of a specific polarization, the reflectivity of the image beam can be increased, and at the same time, the intensity of the double image generated by the reflected image of the window glass 220 can be greatly reduced, that is, it can be confirmed that the same effect as the above-mentioned technology can be obtained.

[0131] Furthermore, instead of the transparent diffusion sheet 55, for example, PDLC (Polymer Dispersed Liquid Crystal) of Santech Display Co., Ltd. can be used, and in the image display state, no voltage is applied to disperse the image light, and in the image non-display state, voltage is applied to form a transparent state to replace the transparent sheet. In addition, the inventors have found through experiments that by making the voltage applied to the PDLC variable to make the dispersion characteristics variable, and modulating the applied voltage in synchronization with the ON / OFF or strength of the image signal, a screen with a new function that can change the transmittance according to the image can be realized.

[0132] In addition, since the image source constituting the above-mentioned image projection device 48 is a liquid crystal panel, when the observer wears polarized sunglasses, a specific polarization is blocked and the image cannot be seen. In order to prevent this, as described above, a wavelength plate 50b such as a λ / 4 plate, a λ / 8 plate, or a λ / 16 plate is arranged between the film or thin film 50a for absorbing or reflecting the P light component in the sunlight beam, which is arranged on the light incident side of the protective cover 50 arranged on the light exit side of the image projection device 48, and the substrate 56. By setting the wavelength plate 50b, the polarization direction of the light beam is unified in a specific direction, and as the optimal polarization angle, the polarization axis of the image light and the polarization direction of the polarized sunglasses can be shifted by a desired amount.

[0133] On the other hand, even with the same polarized light, by rotating the absorption axis, for example by shifting the absorption axis of the polarizing plate on the output side of the liquid crystal panel by more than 30 degrees relative to the absorption axis of the polarized sunglasses, the absorption becomes about 50%, thereby eliminating the problem of not being able to see the image.

[0134] In addition, when the polarization axis is rotated to approach circular polarization, the polarization axis of the image light from the information display system is rotated relative to the S polarization. Therefore, the reflectivity on the window glass 220 is reduced, and the brightness of the image is reduced, so a balance between the two can be made.

[0135] According to the information display system of the present embodiment described in detail above, the image light from the image projection device 48 is light with a narrow diffusion angle (high linear propagation) and only a specific polarization component, just like the image light from the surface-emitting laser image source. Therefore, it is possible to realize an information display system that can, for example, utilize the display window 220 constituting the space to display various information inside or outside the space, significantly improve the utilization efficiency of the display window, display high-quality images with high resolution, and improve the utilization efficiency of the output light from the light source to significantly reduce power consumption.

[0136] In addition, in the case of displaying a larger image, a large-scale liquid crystal display panel 52 in which a plurality of relatively inexpensive liquid crystal display panels are combined and the joints are continuously formed into one body can be used as the image display element, i.e., the liquid crystal display panel 52, which constitutes the image projection device 48 together with the light source device 101. In this case, by making the light beam from the light source device 101 go in parallel to the transparent sheet 51 provided on the window glass 220, and being reflected and diffused in one direction (unidirectionally) by the transparent sheet 51, power consumption can be greatly reduced, and further enlarged image information can be displayed.

[0137] In addition, in the above description, an example is described in which the information display system is applied to a space separated by a display window composed of a transparent member such as glass, i.e., a store, and the interior or exterior thereof is displayed unidirectionally using the display window 220, but the present invention is not limited to such an example. That is, for the information display system of the present invention, as long as it is a predetermined space separated by a transparent member such as glass, the interior or exterior thereof can be displayed unidirectionally using the transparent member separating the space. Other examples of the information display system are described below.

[0138] <In-vehicle information display system>

[0139] The information display system of the above embodiment can make the image light generated by the image projection device 48 and emitted toward the display window 220 as the projection component become (1) image light with a narrow diffusion angle (high linear propagation) and only a specific polarization component like the image light from the surface-emitting laser image source, thereby being able to display high-quality images with high resolution, and can improve the utilization efficiency of the emitted light and significantly reduce power consumption. At the same time, (2) as can be seen from the above-mentioned components, the overall appearance of the device can be configured as a plane (panel). Therefore, using these features, various examples of so-called vehicle information display systems in which the information display system of the above embodiment is applied to vehicles such as automobiles, trains, and airplanes instead of the above-mentioned shops and other spaces are described in detail below.

[0140] Fig. 20 An example of a vehicle information display system mounted on a common passenger vehicle is shown. In this example, the vehicle information display panel 100 of this embodiment is used to display image information on a part of the front window glass 6 (the upper part of the steering wheel 43), a part of the rear window glass and the side window glass 6″ (gray part) or all of them.

[0141] As a specific means of displaying an image on (part of or all of) the window glass of a car, for example, Fig.21 As shown, a large liquid crystal panel 52a (also see Figure 2 52) of the image projection device 48, and a plurality of light guides 203a, 203b, 203c, 203d, 203e, 203f, 203g (also refer to Figure 2 As shown by the hollow arrows in the figure, image light with a narrow diffusion angle (high linear propagation) and a consistent polarization plane is obtained, just like the light from a surface-emitting laser light source.

[0142] These light beams are further directed by light direction conversion panels (not shown in the figure, see Figure 2 The image information is projected onto the front window glass 6, rear window glass 6' and side window glass 6" as the projection surface, and the image is displayed unidirectionally to the inside or outside of the vehicle 1. In addition, at this time, Fig. 22 As shown, the images corresponding to each are displayed in a split manner at the position of the liquid crystal panel constituting the image projection device 48. At this time, since the distance from the image display device to each window glass and the shape of the window glass are different, the original image is deformed so that the projected image can be displayed in a correct shape. The resolution of the large liquid crystal panel 52a is sufficient as long as it is equivalent to 8k.

[0143] Or, if Fig.23 and Fig.24 As shown, instead of the image projection device 48 composed of the large liquid crystal panel 52a, a plurality of image display devices 48a, 48b, 48c, 48d, 48e, and 48f may be arranged on the ceiling of the vehicle body to display images to each window glass. In this case, since the distance from the image display device to each window glass and the shape of the window glass are different, the original image may be deformed so that the projected image can be displayed in a correct shape.

[0144] In the above, an example is described in which an image display area is obtained by pasting a transparent sheet 51 on the window glass 6, and various images are displayed in the image display area using a vehicle information display system. However, the present invention is not limited to this. By providing a reflection enhancement coating for increasing the reflectivity of a specific polarization on the surface of the above-mentioned polarizing plate instead of the above-mentioned transparent diffusion sheet, the reflectivity of the image beam can be increased, and at the same time, the intensity of the double image generated by the reflected image of the window glass 6 can be greatly reduced, so it is confirmed that the same effect as the above-mentioned technology can be obtained.

[0145] Fig.25 and Fig.26 This is an appearance diagram of a vehicle information display system installed in a commercial vehicle such as a bus, a tram (electrically driven rail vehicle), etc. In front of the driver's seat of the vehicle body 1, there are a front window glass 6, a rear window glass 6' (not shown), a side window glass 6" and the like (also collectively referred to as a "windshield") as light-transmitting projection components for projecting and displaying image light. In particular, the inclination angle of the front window glass 6 relative to the vehicle body varies depending on the type of vehicle. In order to achieve the best virtual image optical system, the inventor investigated its curvature radius. As a result, it can be seen that for the front window glass 6 of a bus, a railway vehicle, etc., the curvature radius Rh in the horizontal direction parallel to the ground contact surface of the vehicle and the curvature radius Rv in the direction perpendicular to the horizontal axis have the following relationship, and the curvature radius Rh in the horizontal direction is mostly close to a plane.

[0146] Rh>Rv

[0147] The vehicle information display system utilizes the front window glass 6, rear window glass 6′ and / or side window glass 6″, which are translucent components that divide the space inside the vehicle and serve as projection components that constitute a part of the vehicle, to unidirectionally display image information to the inside or outside of the vehicle. When the driver is driving the vehicle, the driver or passengers in the vehicle can monitor the image information, and on the other hand, the image information can also be displayed to the outside of the vehicle. As a result, the driver and passengers can appropriately display necessary information on the display area such as the front window glass 6 to monitor it inside the vehicle, and on the other hand, the information cannot be monitored from the outside of the vehicle. Alternatively, image information can be displayed to the outside of the vehicle via the rear window glass 6′ and the side window glass 6″ (which may also include the front window glass 6). The displayed information can be monitored from the outside but cannot be monitored from the inside of the vehicle, and will not hinder the driver and passengers from monitoring the external scenery and will not hinder driving.

[0148] In addition, in the vehicle information display system, the vehicle itself is exposed to natural light including sunlight, so it is necessary to deal with the sunlight. However, natural light such as sunlight is Fig. 27 As shown in FIG. 1 , not only is the light of a wide band from ultraviolet to infrared light, but also the polarization direction is a mixture of two polarization directions: light with a vibration direction perpendicular to the traveling direction of the light and light with a polarization direction horizontal to the traveling direction (hereinafter referred to as S polarized light and P polarized light). In particular, in the region where the incident angle to the front window glass 6 exceeds 50 degrees, as shown in FIG. Fig.28 As shown, the reflectivity on the glass surface varies depending on S-polarized light, P-polarized light, and the incident angle.

[0149] Therefore, in the present embodiment, based on the above-mentioned insights of the inventors, that is, considering that most of the sunlight intruding through the front windshield 6 is P-polarized component, in order to suppress external light including sunlight intruding into the information display device, it is especially effective to reduce the P light component. Furthermore, it is effective to utilize the S light component as image light that is emitted from the information display device and reflected into the vehicle and should be recognized by the driver and passengers who are being monitored.

[0150] <Other specific structures of vehicle information display system 1>

[0151] Next, refer to Fig.29 and Fig.30 , other vehicle information display systems and their specific structures obtained by applying the information display system of this embodiment to a vehicle are described in detail.

[0152] Fig.29 and Fig.30The information display system of this embodiment is applied to a vehicle, and the overall structure of the vehicle information display system is shown, which displays image information on a part of the external landscape monitored by the driver through the front window glass 6 as a transparent projection component constituting a part of the vehicle. Here, the front window glass 6 is divided into a plurality of areas, and the image light from the image projection device 48 is diffused and reflected in a part of the area (in this example, the upper part of the front window glass 6), and the driver or the passenger directly monitors the reflected image in one direction. As a result, the driver and the passenger can appropriately display the necessary information in the display area of ​​the front window glass 6 for monitoring, but on the other hand, the information cannot be observed from the outside of the vehicle.

[0153] In the vehicle information display system, if Fig.29 As shown, the image projection device 48 projects high-resolution map information (image of a large high-resolution image display device) from, for example, a smart phone 300, etc., via a light direction conversion panel 54 and a protective cover 50 (hereinafter, the light source device 101 as a backlight device constituting the information display system of this embodiment, the image projection device 48, the light direction conversion panel 54, and the protective cover 50 are collectively referred to as the "information display device" 100) onto the inner surface of the front window glass 6, and is reflected toward the eyes 8 of the observer (driver) via a transparent sheet 51 arranged on the surface of the front window glass 6, thereby displaying an image on the front window glass 6, which will be described in detail below.

[0154] In addition, in this example, an example of using a smartphone 300 as a high-performance portable terminal device equipped with a navigation function that provides map information, etc., is shown. The image can be input from the display screen of the smartphone 300 via a wired connection terminal or by a wireless method such as Bluetooth (registered trademark) or Wifi (registered trademark) to display the image, thereby allowing the driver to monitor high-resolution image information using the vehicle information display system. In addition, although not shown here, the smartphone, like the above-mentioned image projection device 48, includes a control unit composed of a CPU (Central Processing Unit), various solid-state memories such as RAM and ROM that have the function of a working memory or an information accumulation / storage unit, and of course includes a function of generating a desired image and displaying it on the display device (liquid crystal display).

[0155] The more specific structure of the vehicle information display system is further described. The image display element 52 of the image projection device 48 constituting the information display device 100 is composed of, for example, a relatively large liquid crystal display panel with a screen size exceeding 6 inches. Generally speaking, the radius of curvature of the front window glass 6 is mostly different locally, so uneven (vertical and horizontal) deformation occurs in the displayed image depending on the reflection position of the image. Therefore, in order to obtain a correct image when observing the reflected image from the monitoring direction, distortion correction is required. In order to be able to correct the distortion to a level that is not a problem in actual use through this distortion correction, the resolution of the panel is preferably 1280×720 or above.

[0156] In addition, the image display device 48 includes a light source device 101 constituting a light source thereof together with the liquid crystal display panel 52. Fig.29 In FIG. 5 , the light source device 101 is shown above the liquid crystal display panel 52 .

[0157] The liquid crystal display panel (element) 52 is as follows Fig.29 As shown, a backlight device, namely, a light source device 101, is used to obtain a highly directional illumination beam, and the image light modulated according to the input image signal is emitted toward a transparent sheet 51 provided on the front window glass 6. Fig.29 In the embodiment, the vehicle information display system is configured to include, in addition to the image projection device 48 having the light source device 101 and the liquid crystal display panel 52, a light direction conversion panel 54 for controlling the directional characteristics of the outgoing light beam 30 from the light source device 101, and a narrow angle diffusion plate (not shown) provided as required. That is, polarizing plates are provided on both sides of the liquid crystal display panel 52 so that the intensity of the light is modulated according to the image signal and image light of a specific polarization is emitted. Thus, a high-resolution image (an image of a large high-resolution image display device) from a smartphone 300 or the like is emitted to the front window glass 6 by the light direction conversion panel 54, and is reflected to the eyes 8 of the observer (driver) by the transparent sheet 51 provided on the surface thereof.

[0158] In addition, as shown in the figure, the image projection device 48 constituting the vehicle information display system includes a light source device 101, a liquid crystal display panel 52, etc. The structure and function of the image projection device 48 including the light source device 101 have been indicated as an embodiment of the image display device in the above text and will not be described in detail here. The image projection device can output almost all of the light generated by the LED as parallel light, can improve the utilization efficiency of the generated light, and further, can further improve its uniform lighting characteristics while including a modular S-polarized light source device, and can be manufactured in a small and low-cost manner.

[0159] In addition, although not shown here, by adopting the structure and characteristics as described above Figure 5 to Figure 7The cylindrical lens and microlens array sheet (not shown) shown in the figure can obtain image light with a narrow diffusion angle (high linear propagation) and only a specific polarization component, just like the image light from a surface-emitting laser image source. By utilizing such image light, the image light from the image projection device 48 can efficiently reach the eyes 8 of the observer outdoors or indoors, thereby realizing a low-power vehicle information display system that can display high-quality images with high resolution and further reduce the output of the image projection device 48.

[0160] In addition, the light direction conversion panel 54 provided on the lower surface of the image projection device 48 is also connected to the above Figure 8 The same as that described in the related records, and its structure and function are not described in detail here. By using the light direction conversion panel 54, the light emitted from the liquid crystal display panel 52 of the image projection device 48 constituting the vehicle information display system, that is, the image light, can be sent to the transparent sheet 51 provided on the front window glass 6 without being observed by the driver and the passenger inside the vehicle. After that, the image light is reflected and diffused in one direction by the transparent sheet 51, and its reflected image is observed by the driver. That is, by using the light direction conversion panel 54, the image light itself from the image projection device 48 will not be directly observed from the inside of the vehicle, so the image light will not hinder driving, and the driver or the passenger can only monitor the reflected image of its reflected light.

[0161] In addition, the protective cover 50 disposed in contact with the ceiling surface of the vehicle and provided on the upper surface of the light direction changing panel 54 is also provided in the same manner as the above-mentioned Fig. 9 The contents are the same as those already described in the related records, and the structure and function thereof will not be described in detail here. The protective cover 50 can be used to reduce the problems caused by external light reflection in the vehicle information display system, especially when the driver is driving the vehicle.

[0162] In addition, the sunlight incident on the front window glass 6 from an oblique direction has its S polarized light reflected and its P polarized light transmitted to the transparent sheet 51. The transparent sheet 51 is as described above. Fig.16 As described in the relevant records, it is composed of a polarizing plate 57 that transmits S light and a transparent diffusion sheet 55. It is transparent when no image is displayed and will not hinder the driver from monitoring the scenery outside the vehicle. On the other hand, when the image is displayed, by diffusing and reflecting the image light, a one-way display of the image information can be achieved, which can be observed by the driver and passengers.

[0163] In addition, as already explained, Fig.17The structure shown can also achieve the same effect. In this case, the haze (HAZE) of the transparent sheet 51, which is defined by the ratio of the diffuse transmittance to the parallel light transmittance, is not a problem in practice as long as it is 10% or less, but it is preferably 4% or less. The haze of the window glass for automobiles is 2% or less.

[0164] On the other hand, the image light from the image projection device 48 constituting the vehicle information display system is S-polarized light, so when it is obliquely incident, it is scattered in a state of high reflectivity inside the transparent diffusion sheet 55 constituting the above-mentioned transparent sheet 51 and emitted to the observer. On the other hand, a part of the image light has its polarization direction disturbed due to scattering, and is diffused and transmitted through the transparent diffusion sheet 55 and emitted to the front window glass 6. Since the refractive index difference is small at the incident surface of the front window glass 6, the degree of double images caused by the reflected light is low.

[0165] In contrast, the intensity of the reflected light generated on the exit surface (surface in contact with the outside world) of the front window glass 6 is mostly S polarized components, so the reflectivity is large. The image light reflected on this surface is absorbed when it passes through the polarizing plate 57 again after reflection, so it will not return to the observer side. Therefore, no double image is generated by the reflected image of the front window glass 6, so the image quality is greatly improved. In addition, similarly, as a reflection surface of the image, the above-mentioned transparent sheet 51 is pasted on the stacking mirror instead of the front window glass 6, and of course the same effect can be obtained.

[0166] Using the above-mentioned transparent sheet 51, from the above-mentioned Fig.16 , Fig.17 It can also be known that under the specified conditions during the day, before the image projection device 48 including the light source device 101, the liquid crystal display panel 52, and the device including the light direction conversion panel 54, etc., and the light direction conversion panel 54 and the protective cover 50 arranged on the upper surface thereof, which constitute the vehicle information display system, the P-polarized light sunlight component after passing through the front window glass 6 (in the stacking mirror mode, it also passes through the stacking mirror after passing through the window glass) is absorbed, thereby preventing it from returning to the liquid crystal display panel and the polarizing plate.

[0167] In the above example, the case where the reflective transparent sheet 51 is used as the one-way transparent sheet 51 provided on the front window glass 6 is described, but it is also possible to use the above-mentioned Fig.18 The transmissive transparent sheet 51' described in the above makes the image beam diffuse in one direction, that is, outside the vehicle. In this case, a polarizing plate and a phase difference plate that transmit P light are provided on the image beam incident surface of the transparent diffusion sheet 55 constituting the transparent sheet 51', so as to prevent the image beam reflected on the transparent diffusion sheet 55 from returning to the vehicle interior (the space where the vehicle information display system is provided). As a result, the driver will not be hindered from driving by the image presented on the front windshield 6.

[0168] The optimal phase difference of the phase difference plate 58 disposed between the polarizing plate 57 and the transparent diffusion sheet 55 can be selected based on the diffusion characteristics of the transparent diffusion sheet. When the diffusion angle is large, it is preferably close to λ / 4. When the diffusion angle is small, good conversion performance can be obtained by combining it with a λ / 8 plate or the like. Fig.19 The same effect can also be obtained by Example 2 of the one-way transparent sheet described in .

[0169] In the vehicle information display system including the light source device 101, the image projection device 48 including the liquid crystal display panel 52 and the light direction conversion panel 54 described in detail above, as shown in FIG. Fig.29 As shown by the middle arrow, a large-scale high-resolution image projection device 48 is provided at a position (ceiling surface in the figure) corresponding to the image display area of ​​the upper area of ​​the front window glass 6, which is a transparent member for dividing the interior space of the vehicle, so that the driver and the passenger can directly monitor the reflected image by reflecting the displayed image on the front window glass. At this time, it is possible to display high-quality images with high resolution by using image light having a narrow diffusion angle (high straight-line propagation) and only a specific polarization component, such as image light from a surface-emitting laser image source, and to improve the utilization efficiency of the emitted light and significantly reduce power consumption.

[0170] <Other specific structures of vehicle information display system 2>

[0171] Furthermore, in the above-mentioned vehicle information display system, the vehicle window glass including the front window glass 6 and the side window glass 6″ that partition the vehicle space is used to display images through the image projection device 48, the light direction conversion panel 54, etc., but the present invention is not limited to this. The image can also be displayed using the rear window glass, or a head-up display (HUD) type information display device (hereinafter referred to as "HUD device") can be installed and used at the same time. An example of this is described below.

[0172] then, Fig.31 Indicates that the above large vehicles are replaced in appearance Fig.30 The example of a vehicle information display system mounted on a common passenger car shown in the figure uses an image display device 704 and a light source device 710 of a HUD device 700 provided in place of the above-mentioned image projection device 48 and light direction conversion panel 54 to display an image in one direction on a portion of the front window glass 6 (the upper portion of the steering wheel 43) and a portion of the side window glass 6″ facing the interior or exterior of the vehicle.

[0173] Here, a known general device can be adopted as the HUD device, and here, as an example, it is roughly described below.

[0174] Fig.31This is a schematic structural diagram showing the structure of the HUD device 700 and its surrounding equipment. Here, in order to form a virtual image V1 in front of the vehicle in the line of sight (eye point) of the driver 8, a transparent sheet 51 arranged on the front windshield 6 is used to diffusely reflect various information reflected by the projection component 6 (inner surface of the front windshield) into the vehicle and display it as a real image.

[0175] The HUD device 700 includes: an image display device 704, which corresponds to the image projection device 48 and is used to generate image light of information to be displayed; and a light source device 710, which corresponds to the light source device 101 and is used to provide light to the image display device 704. In order to control the diffusion distribution of the image light from the image display device 704, a cylindrical lens is provided on a part of the surface of the image display device 704, and control can be performed in one direction by optimizing the lens shape.

[0176] The image light beam from the HUD device 700 is emitted from the opening (not shown) toward the front window glass 6. That is, in the HUD device 700 constituting the vehicle information display system, by using the above-mentioned cylindrical lens and microlens array sheet, it is possible to obtain image light having only a specific polarization component and a narrow diffusion angle (high linear propagation) like the image light from the surface-emitting laser image source. By using such image light, the image light can also efficiently reach the eyes 8 of the observer outdoors or indoors, thereby realizing a vehicle information display system that displays high-quality images at high resolution and further reduces the output of the HUD device 700 and has low power consumption.

[0177] In addition, the HUD device 700 includes a control device 740 for controlling its backlight. The optical components including the image display device 704 and the backlight reflect and diffuse the display image of the image display device 704 on the transparent sheet 51 attached to the front windshield 6, thereby allowing the display image to be directed to the driver's line of sight 8. The image display device 704 may be, for example, an LCD (Liquid Crystal Display) including a backlight.

[0178] The illustrated control device 740 constituting the HUD device obtains various information as foreground information (i.e., information to be displayed in front of the vehicle through the above-mentioned virtual image) from the navigation system 761. The various information includes the speed limit and number of lanes of the road corresponding to the current position of the vehicle, the planned movement path of the vehicle set in the navigation system 761, etc.

[0179] The driving assistance ECU 762 is a control device that controls the drive system and the control system according to the obstacles detected by the monitoring results of the surrounding monitoring device 763, thereby realizing driving assistance control. As such driving assistance control, for example, known technologies such as cruise control, adaptive cruise control, pre-collision safety system, and lane keeping assistance are included. The surrounding monitoring device 763 shown in the figure is a device that monitors the conditions around the vehicle. As an example, it is a camera that detects objects around the vehicle based on images captured around the vehicle, and a detection device that detects objects around the vehicle based on the results of sending and receiving detection waves.

[0180] The control device 740 of the HUD device obtains information (such as the distance to the vehicle in front, the direction of the vehicle in front, the location of obstacles and signs, etc.) from the driving assistance ECU 762 as foreground information. Furthermore, the ignition (IG) signal and the vehicle status information are also input to the control device 740. Among these information, the vehicle status information is information obtained as vehicle information, which does not need to be displayed with high resolution, and includes, for example, warning information indicating that a predetermined abnormal state has been reached, such as the remaining amount of internal combustion engine fuel and the temperature of the coolant.

[0181] In addition, it also includes the operation result of the direction indicator and the driving speed of the vehicle, and also includes gear information, etc. The control device 740 is started when the ignition signal is input. In addition, the projected component 6 can be any component that can be projected with information, and can be not only the front window glass mentioned above, but also a stacking mirror, as long as it can form a real image in front of the vehicle in the driver's line of sight 8 for the driver to observe.

[0182] Then, in Fig.32 2 shows an example of the arrangement of the image projection device 48, the transparent sheet 51 and / or the HUD device 700 in the cabin of a car. Fig.32 (a) shows the system configuration corresponding to a car with a steering wheel on the left side. Fig.32 (b) shows the system configuration corresponding to a car with the steering wheel arranged on the right side.

[0183] exist Fig.32In the HUD image display area (1a), the HUD device 700 is used to reflect on the front windshield 6 to display image information, and in the image display area (1b) (corresponding to the pasting area of ​​the transparent sheet 51), a device (herein, indicated by the reference numeral 100 as a "vehicle information display device") including the light source device 101, the image projection device 48 of the liquid crystal display panel 52, and the light direction conversion panel 54 is used to make the image information reflected by the front windshield 6 so that the driver can monitor the reflected image. At this time, as shown in the figure, the image display area (1b) is preferably set at the upper part of the front windshield 6, and the HUD image display area (1a) is preferably set in a range or area that does not hinder the driver from monitoring the scenery outside the vehicle, such as a range where the engine hood of the vehicle can be monitored.

[0184] like Fig.32 As shown, the vehicle information display device 100 is arranged on the roof surface of the vehicle at a position connected to the windshield 6, facing the steering wheel 43, while the HUD device 700 is arranged inside the instrument panel 47 between the windshield 6 and the steering wheel 43, facing the steering wheel 43 at a position connected to the windshield 6. As a result, it is possible to provide a vehicle information display system in which, when the driver is driving the vehicle, the image of the large-scale high-resolution image display device is reflected on the windshield 6 by the vehicle information display device 100, so that the driver or the passenger can monitor the reflected image of the image in the external landscape monitored through the windshield 6, that is, a part of the windshield 6, or can also display information from the HUD device 700 as needed.

[0185] That is, the image display area (1b) on the window glass 6 to which the transparent sheet 51 is attached reflects the image light from the vehicle information display device 100 so that the driver can monitor. At this time, the image display area (1b) can simulate the augmented reality by, for example, superimposing the scenery monitored by the driver while driving. The image presented at this time is preferably set in a range or area that does not hinder the driver from monitoring the scenery outside the vehicle.

[0186] In addition, you can also Fig.32 The interior rearview mirror 71 shown is provided with a camera 72 for monitoring the driver's status and the situation inside the vehicle. For example, the emission direction of the image light from the vehicle information display device 100 can be controlled to match the height of the driver's eyes.

[0187] <Other modification examples of vehicle information display system: external display>

[0188] According to the embodiment described in detail above, when the driver is driving the vehicle, necessary image information can be displayed unidirectionally with high resolution to the driver and passengers inside the vehicle for monitoring via the windshield constituting a part of the vehicle, i.e., the front window glass 6 as the projection component.

[0189] In this case, the information cannot be monitored from the outside of the vehicle. However, the vehicle information display system of the present invention is not limited to the above-mentioned embodiment, and can also display image information to the outside of the vehicle. That is, not only through the above-mentioned front window glass 6, but also through the rear window glass 6' and side window glass 6" as the windshield, the image information can be displayed to the inside or outside of the vehicle in the same way as described above.

[0190] For example, in the system of the present embodiment, information indicating the vehicle status, such as "empty vehicle", can be displayed on a part of the front window glass 6 of the taxi, and then displayed on the rear window glass 6' and the side window glass 6", or other information such as publicity and advertisement can be displayed on the outside of the vehicle. In addition, in vehicles such as buses and trains, information such as their routes and destinations can also be displayed unidirectionally on the front window glass, rear window glass, side window glass, etc. to the outside of the vehicle. The following describes the structure of the vehicle information display system in the case of displaying information to the outside.

[0191] Fig.33 The system is a system for displaying necessary image information in a high resolution to the outside of a vehicle through the projection component, that is, the windshield 6, for monitoring. More specifically, an example of displaying the taxi status (such as "empty") on the windshield of a taxi is shown here. Fig.32 In the structure shown in the figure, a transparent sheet 51′ (see Fig.18 ), the front window glass 6 is used to diffuse and transmit the image light from the vehicle information display device 100', so that the image is as shown Fig.18 As shown by the arrow in the figure, the information is transmitted to the outside of the vehicle for display, and pedestrians, etc. can be monitored. As a result, the driver or the passenger can display necessary information to the outside of the vehicle on the front window glass 6, but the display will not hinder the view outside the vehicle monitored from the inside of the vehicle, and will not hinder the driver's driving.

[0192] In addition, by providing a reflection enhancement coating for increasing the reflectivity of a specific polarization on the back of the polarizing plate instead of the transparent diffusion sheet 55 of the transparent sheet 51', the reflectivity of the image beam can be increased, and at the same time, the intensity of the double image generated by the reflected image of the front window glass 6 can be greatly reduced. That is, it was confirmed that the same effect as the above-mentioned technology can be obtained.

[0193] Furthermore, the transparent diffusion sheet 55 may be replaced by, for example, PDLC (Polymer Dispersed Liquid Crystal) from Santech Display Co., Ltd., which disperses image light by not applying voltage in the image display state and forms a transparent state by applying voltage in the image non-display state.

[0194] The transparent sheet 51' is composed of a polarizing plate 57 that transmits S light and a transparent diffusion sheet 55 as described above. Here, a film is used that is formed by melting and stretching a thermoplastic polymer dispersed with zirconium oxide nanoparticles or diamond nanoparticles having a large refractive index, such as "KALEIDO SCREEN" manufactured by JXTG Energy Co., Ltd. (refer to the above-mentioned patent document 2). By using this film, it is transparent when no image is displayed, and diffuses and reflects the image light when the image is displayed. Thus, the image information can be displayed externally without allowing the driver and passengers to observe the image information and without obstructing the monitoring of the scenery outside the vehicle.

[0195] The role of the transparent sheet 51' at this time is described. The transparent sheet 51' is composed of a polarizing plate 57, a transparent diffusion sheet 55 and a phase difference plate 58. As described above, for sunlight incident from an oblique direction, the S polarized light is reflected and the P polarized light is transmitted to reduce the illumination of the sunlight. At this time, the polarization axis of the P polarized light is rotated by the phase difference plate 58, so that a part of the sunlight is absorbed by the polarizing plate. As a result, the damage to the image projection device 48 caused by sunlight can be dispersed.

[0196] On the other hand, in the transparent diffusion sheet 55 (refer to Fig.18 ) will be reflected by the rear window glass 6' and return to the inside of the vehicle. This light will block the driver's field of vision, thus causing obstacles to driving. Therefore, in this embodiment, by arranging a phase difference plate 58 between the rear window glass 6' and the polarizing plate 57 and using the polarizing plate to absorb the reflected light, the information of the image light will not be observed by the driver and passengers in the vehicle, but will be displayed unidirectionally to the outside of the vehicle.

[0197] Of course, using Fig.19 The same effect can be obtained by the example 2 of the unidirectional transparent sheet shown. In this case, the image light information will not hinder the driver or passengers in the car from monitoring the scenery outside the car, and will not hinder driving. The haze (HAZE) of the transparent sheet 51, which is defined by the ratio of the diffuse transmittance to the parallel light transmittance, is not a problem in practical use as long as it is 10% or less, but it is preferably 4% or less. The HAZE of the window glass for automobiles is 2% or less.

[0198] As described above, the information display facing the outside of the vehicle using the front window glass 6 and a part of the windshield such as the rear window glass and the side window glass is particularly suitable for displaying the above-mentioned "empty taxi" information indicating the empty taxi state to pedestrians on the road. In addition, the vehicle information display system of this embodiment can not only display image information on the front window glass as described above, but also can display image information on the rear window glass 6' and the side window glass 6" (see FIG. 1 ) in a large vehicle such as a bus or a train, which are part of the windshield of the vehicle. Fig.25 , Fig.26 The projection components such as the display device and the like are used to display various information including publicity, advertisement, and notice. The structure and function of the vehicle information display system in the case of displaying information outside the vehicle are further described below.

[0199] exist Fig.34 In the embodiment, as an example, the projection component constituting a part of the vehicle displays information to pedestrians or the like outside the vehicle via the rear window glass 6' constituting the vehicle. As a result, the driver and the passengers can monitor the necessary information on the front window glass 6 (see Fig.25 The rear window 6' can also display information to the outside of the vehicle. In addition, the driver and passengers cannot monitor the information displayed to the outside, so the driver's field of vision will not be obstructed. In other words, the information displayed to the outside of the vehicle will not hinder the driver or passengers in the vehicle from monitoring the external scenery.

[0200] In this example, a vehicle information display device 100' is arranged above a rear window glass 6' which is a projection target component constituting a part of the vehicle, and its image light is projected onto an image display area (1e) set on the entire surface or a part of the rear window glass 6', thereby displaying image information.

[0201] In this example, the image display area of ​​the rear window glass 6' is of course provided with the above Fig.18 and Fig.19 The transparent sheet 51' shown. In addition, the projection component for displaying image information one-way outside the vehicle is not limited to the front window glass 6 and the rear window glass 6' mentioned above. For example, the side window glass 6" (see Fig.25 , Fig.26 , Fig.31 In this case, of course, the vehicle information display device 100' is arranged on a component near the side window glass 6" (for example, an adjacent ceiling surface, a part of the window frame structure, etc.), and the above-mentioned Fig.18 and Fig.19 A transparent sheet 51' is shown, but is not shown in the figure here.

[0202] The information display on the side window glass 6 ″ is suitable for displaying messages such as “Please wait” or “Please get on” to passengers on the road in a taxi, for example.

[0203] Furthermore, in the above-described example, the vehicle information display devices 100 and 100′ are described in which the image information to be displayed is displayed unidirectionally on the outside or inside of the vehicle using the projection components constituting a part of the vehicle, namely the front window glass 6, the rear window glass 6′, and the side window glass 6″. However, the present invention is not limited to this, and for example, the vehicle information display device 100′ that displays information on the outside of the vehicle can be appropriately combined with the vehicle information display device 100 that displays information on the inside of the vehicle.

[0204] Therefore, for example, when applied to public transportation vehicles such as buses and trains, various information including publicity, advertisements, and notifications can be displayed to the public outside the vehicle through the rear window glass 6' and the side window glass 6", and effective information can be displayed to the public. In addition, as described above, as a vehicle information display device, a head-up display (HUD) 700 can also be installed and used at the same time.

[0205] Furthermore, instead of the above-mentioned transparent diffusion sheet 55 (refer to Fig.18 ), for example, PDLC (Polymer Dispersed Liquid Crystal) of Santech Display Co., Ltd. is used, and a sheet or film capable of absorbing or reflecting a specific polarization is formed on the incident side of the image light, wherein no voltage is applied in the image display state to make it white, thereby being able to display the image light inside and outside the vehicle. In the state where the image is not displayed, it can be replaced by a transparent sheet by applying a voltage to make it transparent. When the driver needs to observe the rear view, such as when switching to reverse gear, or when the driver's viewpoint is confirmed to move to the rearview mirror or the rearview mirror inside the vehicle through the driver monitoring camera, a voltage is applied to a part of the PDLC to make the entire surface of the PDLC or a part of it transparent, thereby ensuring rear visibility. The above-mentioned sheet or film can reduce the situation where the image light returns to the driver's side, and will not cause driving obstacles.

[0206] Furthermore, it is also possible to display the image from the HUD device 700 on the window glass 6 using a display device including the image projection device 48 and the light direction conversion panel 54. An example of this is shown in the above Fig.29 , Fig.31The structure and operation of the HUD device 700 are the same as those described above, and the structure and operation of the vehicle information display device 100 are also the same as those described above. In addition, in this case, as in the above, the utilization efficiency of the generated light can be improved, and further, while further improving its uniform lighting characteristics, it can be manufactured in a small and low-cost manner, including a modular S-polarized light source device.

[0207] In addition, in the case of displaying a larger image through the projected components that constitute a part of the vehicle, namely the front window glass 6, the rear window glass 6′, and the side window glass 6″, in the above-mentioned vehicle information display devices 100 and 100′, as the image display element 52 that constitutes the image projection device 48 together with the light source device 101, a large liquid crystal display panel 52 can be used that is formed by combining a plurality of relatively inexpensive liquid crystal display panels so that the joints are continuously formed into one body. In this case, by making the light beam from the above-mentioned light source device 101 go in parallel to the transparent sheet 51 provided on the window glass 6, and reflecting and diffusing it in one direction (unidirectionally) by the transparent sheet 51, it is possible to significantly reduce power consumption in a relatively simple and inexpensive manner and display further enlarged image information.

[0208] In the above-mentioned vehicle image display system of the HUD device type of the present invention, when the image light from the image display device 48 is parallel light, for example, the distance from the window glass to the observer's eye 8 is 80 cm, and the distance at which the virtual image can be seen (the position reflected by the window glass) is used as a parameter, the relative size of the reflected image (virtual image) that can be seen on the window glass when the horizontal size of the screen of the image display device 48 is 10 inches and 20 inches is calculated. The results are shown in Fig.35 .

[0209] If the virtual image is formed on the upper part of the axis LL' at the eye level of the observer, the virtual image will appear in the air, and the observer will feel motion sickness when the car shakes up and down. Therefore, the virtual image is preferably displayed on the horizontal line LL' or below it. According to the experimental results of the inventors, the angle β between the virtual image and the horizontal axis is preferably in the range of 0 to 8 degrees, and in the case of realizing augmented reality, it is more preferably in the range of 0 to 4 degrees. When β is 4 degrees, the virtual image distance is 20m. When the horizontal size of the image display device is 10 inches, the virtual image obtained by reflection from the window glass is equivalent to 250 inches, and when it is 20 inches, it is equivalent to 500 inches.

[0210] and then, Fig.36 The image light control film 70 (see Fig.15 ) is a cross-sectional view of an example in which the image display device 48 is mounted in a car. Fig.36 In the embodiment, the light source device 101 is Figure 3 , Figure 4 Similarly, for example, a light guide 203 formed of plastic or the like and having a light beam direction conversion section 204 disposed on the surface or inside thereof, an LED element 201 as a light source, a reflector 205, a phase difference plate 206, etc., is mounted on the upper surface thereof with a liquid crystal display panel 52 having a polarizing plate 49 disposed on the light source light incident surface and the image light emitting surface, thereby constituting an image projection device 48, and the above-mentioned Fig.15 The image light control film 70 shown. The image light from the liquid crystal display panel 52 is emitted in a specific direction (the front window glass 6 in the figure), and a part of the light is blocked by the black portion 70b, so it will not directly enter the eyes of the observer, so the light directly from the image display device 48 will not become an obstacle to driving.

[0211] The image light control film 70 has the function of preventing the image light from going directly to the observer. On the other hand, the image light passes through the transparent portion 70a and is reflected by the front window glass 6, etc., so that the driver who is the observer can recognize the image light. As the image light control film 70, for example, a view angle control film (VCF: View Control Film) of Shin-Etsu Polymer Co., Ltd. is suitable. Its structure is to alternately configure transparent silicon and black silicon, and configure synthetic resin on the light incident and emission surfaces to form a sandwich structure, so it is expected to achieve the same effect as the image light control film 70 of this embodiment.

[0212] The spacing h between the transparent portion 70a and the black portion 70b of the viewing angle control film is preferably less than 1 / 3 of the pixels of the image to be displayed. At this time, regarding the thickness W, when it is desired to obtain a viewing angle α greater than 90 degrees, h / w is greater than 1.0, and when it is desired to obtain a viewing angle α less than 90 degrees, h / w is less than 1.0. On the other hand, the haze (HAZE) of the transparent sheet 51, which is defined by the ratio of the diffuse transmittance to the parallel light transmittance, is practically no problem as long as it is less than 10%, but it is preferably less than 4%.

[0213] Various embodiments have been described in detail above, but the present invention is not limited to the above embodiments, and includes various variations. For example, the above embodiments describe the entire system in detail in order to explain the present invention in an easy-to-understand manner, but are not limited to including all the structures described. In addition, a part of the structure of a certain embodiment can be replaced with the structure of another embodiment, and the structure of another embodiment can be added to the structure of a certain embodiment. In addition, for a part of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0214] Description of Reference Numerals

[0215] 1…car (vehicle) body, 6…front window glass, 6′…rear window glass, 6″…side window glass, 100…vehicle information display device, 101…light source device, 48…image projection device, 49…reflective polarizing plate, 52…liquid crystal display panel (element), 50…protective cover, 51…unidirectional transparent sheet, 54…light direction conversion panel, 55…transparent diffusion sheet, 57…polarizing plate, 58…phase difference plate, 70a…transparent part, 70b…black part, 202…LED substrate, 203…light guide, 205…reflective sheet, 220…window (window glass), 300…smartphone.

Claims

1. An information display system, which displays images one-way inside or outside a space via a transparent projection component constituting the space, characterized in that: include: An image projection device is disposed inside the space and modulates the light beam from the light source to generate image light for projection; a transparent sheet disposed on an inner side surface of a display area provided in a portion of the projection component; and a light direction converting unit for directing the image light from the image projection device toward the transparent sheet in the display area, The image projection device includes an image light characteristic conversion unit, which is used to convert image light from the light source constituting the image projection device into image light having a narrow diffusion angle and consisting of specific polarization components. The light direction converting unit is a linear Fresnel lens.

2. The information display system according to claim 1, characterized in that: The image light characteristic conversion unit of the image projection device includes a cylindrical lens and a polarizing plate for controlling the diffusion distribution of the image light.

3. The information display system according to claim 1, characterized in that: The space is divided by the transparent projected component, and the space is a store.

4. The information display system according to claim 1, characterized in that: The image projection device is composed of a single liquid crystal panel or a combination of multiple liquid crystal display panels.

5. The information display system according to claim 1, characterized in that: The transparent sheet includes a phase difference plate, an absorption-type polarizing plate that absorbs light of a specific polarization, and a transparent diffusion sheet having a light diffusion function, and projects the image light whose direction is converted by the light direction converting unit into or outside the space.

6. The information display system according to claim 1, characterized in that: In the light source constituting the image projection device, a divergent light source emitting natural light is formed into a surface light source by a light guide, and the shape of the end surface of the light guide makes the light of the divergent light source enter the image light characteristic conversion unit as a substantially parallel beam.

Images